1. Field of the Invention
This invention relates to solder, brazing and welding compositions having improved physical properties by reason of incorporation of a reinforcing material in particulate or fibrous form into a conventional solder, brazing or welding alloy.
2. Prior Art
Lead based and tin based low melting point solders are well known in the art. Representative alloys of this type are classified in ASTM Designation B-32-60T, revised 1966. These alloys may contain from about 30% to about 98% lead by weight, up to about 5.5% antimony, and fractional percentages of aluminum, arsenic, bismuth, copper and iron. Tin based solder alloys may contain from about 30% to about 99% tin by weight, up to about 20% lead, up to about 5.5% antimony, up to about 5% copper, and fractional percentages of aluminum, arsenic, bismuth, and iron.
Other solder alloys are known in which antimony may be present in amounts up to 20% by weight, and in which cadmium and/or zinc may be substituted for lead (or tin) in amounts up to 90% by weight.
Brazing alloys are high melting point compositions used to join stainless steels, copper, brass, nickel based alloys, so-called super alloys and the like, and may contain copper, nickel, chromium, silver and zinc in predominant amounts.
A brazing alloy is also available which has a glassy matrix rather than a crystalline matrix. This is commonly referred to as metallic glass, i.e., an amorphous alloy. Metallic glass is made by very rapidly cooling a boron-containing alloy in the form of a thin film or ribbon. This may then be used as a brazing shim. After the brazing operation is conducted, the alloy solidifies in a crystalline form.
Welding alloys are ordinarily provided in the form of electrodes and may contain stainless steel, copper, nickel, cobalt, titanium and/or magnesium. Such electrodes may be produced either by a powder metallurgy operation or by casting an ingot and extruding or swaging the ingot down to the desired size.
U.S. Pat. No. 4,415,950, issued Nov. 15, 1983 to R. D. Weeks, discloses an electrical component in the form of a solid electrolytic capacitor, having a capacitor body of sintered material and impregnated with a solid electrolyte, a tin containing solder alloy coating on the outside of the capacitor body, and a conductive coating layer, in contact with the solder layer, having pure silver and pure copper particles interspersed therein.
U.S. Pat. No. 4,474,323, issued Oct. 2, 1984 to R. D. Weeks, is a division of U.S. Pat. No. 4,415,950 and claims a method of making an electrical component which includes forming a paint containing, by weight, 10 to 40% silver particles, 50 to 10% copper particles, 2 to 12% polymeric binder, 30 to 60% solvent, and 0.01 to 1% wetting agent. This paint is applied over the solder layer to form the conductive coating layer.
U.S. Pat. No. 4,625,261, issued Nov. 25, 1986 to R. D. Weeks et al, discloses an electrical component comprising a tin-containing solder alloy body and a conductive coating layer having silver particles and uncoated copper particles in intimate mixture.
U.S. Pat. No. 4,699,763, issued Oct. 13, 1987 to S. D. Sinharoy et al, discloses an electrical contact material comprising a pressed and sintered powder having about 0.5 to about 10 weight percent graphite fibers, about 0.1 to about 3% powdered wetting agent, and remainder essentially powdered silver. The wetting agent is nickel, iron, cobalt, copper, or gold, or mixtures thereof. The method of production involves making a slurry of the materials in a volatile hydrocarbon solvent, drying the mixture, and repeatedly pressing and sintering.
The electrical contact material of '763 is alleged to exhibit increased resistance to electrical erosion, high strength, and minimal temperature rise due to make-and-break of an electrical circuit. The contact material is brazed to a contact by a silver-copper solder layer having a thickness of 0.003 to 0.004 inch (0.076 to 0.10 mm).
The above-mentioned patents do not relate to modification of solder, brazing or welding alloys, aside from a reference to minimizing "leeching" of silver particles from a paint layer into a tin solder layer. To the best of applicant's knowledge, there have been no disclosures of addition of reinforcing materials to solder and brazing alloys for the purpose of improving the mechanical properties thereof.
A genuine need exists for solder, brazing and welding compositions which exhibit improved creep strength, modulus of elasticity, ultimate tensile strength, wear resistance, freezing range, usable service temperature, thermal conductivity and electrical conductivity, and a lower coefficient of thermal expansion, for all usual applications of solders, brazing and welding compositions.